32715 Make all notes use equal padding

What does this MR do?

Make all notes share the same padding: 16px 10px. Creates equal padding with markdown. Half padding (8px) under header. Removes padding from system notes.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #32715 (closed) Closes #32467 (closed)